The present invention relates to a station for forming stacks of layers of articles in a machine for packaging rolled paper products.
There are machines for packaging stacks of articles, in particular substantially cylindrical articles, into relative wrappings obtained from a sheet of heat-weldable material.
In the following, the reference will be made paper rolls, for sake of simplicity.
The above-mentioned machines include:
a grouping station, in which layers of rolls are defined, with each layer being formed by rolls arranged one beside another in an ordered way;
a station, in which a stack is formed by one or two layers arranged one over the other, and
a wrapping station, in which the stack is wrapped with a heat-weldable material to obtain the above mentioned wrapping.
The present invention relates to the station, in which the stack is formed.
There are already known stations for forming stacks of layers of cylindrical articles.
In particular, each of the documents U.S. Pat. No. 3,455,085, IT 1.225.033 describes a station including:
a surface for supporting layers of cylindrical articles coming from the grouping station, situated upstream, with the final part of the supporting surface turned toward the wrapping station and driven into a motion so as to form a kind of pendulum, so as to define as many positions as the layers to be obtained;
a plurality of receiving planes, which are situated one over another and whose number corresponds to the number of layers, with each of the receiving planes having one end turned toward the grouping station and being adjacent and situated at the same level as the moving end of the above mentioned pendulum in a corresponding position of the latter;
first means for moving the pendulum to define one of the positions;
second means for moving said layers along the supporting surface, acting in time relation with said first means;
third means for each of said receiving planes, equipped with pushing elements, which move forward synchronously and aligned vertically above the receiving planes.
The stack is formed on the lower receiving plane. Since the layers are moved with the same speed, there is no reciprocal rubbing between different layers during the stack forming.
The above-mentioned first means are connected to the pendulum and are, therefore, also driven into oscillation. Also motor means are likewise fastened to the pendulum to impose the oscillation with respect to the hinge with the supporting surface.
It is to be pointed out that the inertia of the pendulum and the devices connected thereto affect the time required for the passage of the pendulum from one position to the subsequent one.
Moreover, during its oscillation, the pendulum carries rolls, which may detach therefrom after a given speed has been reached.
This reduces the production rate of the stack forming station.
The object of the present invention is to propose a station for forming a stack of layers of articles that solves the above-mentioned problems, in particular that does not have parts moving with an oscillating alternate motion, which connect the plane supporting the layers of articles arriving from the grouping station, with the working planes for receiving the layers.
Another object of the present invention is to propose a station, in which the articles are driven into a continuous motion, so as to increase the production rate with respect to the known stations fulfilling the same function.
A further object of the present invention is to propose a station for forming a stack of layers of articles which does not jeopardize the operation of the grouping station, situated upstream, nor of the wrapping station, situated downstream, and which consists of combination of devices and elements easy to manufacture and of safe functionality.
The above-mentioned objects are obtained by a station for forming stacks of layers of articles, situated downstream of a station for feeding the layers, said forming station including:
a horizontal supporting surface;
a first surface, situated after said horizontal support surface and distanced therefrom, so as to define a window, with the dimension of said window allowing one layer of said articles layers to pass freely therethrough;
first moving means for moving the layers along said support surface and first surface;
a stationary descending ramp, which begins from the initial part of said window and extends downwards;
a second horizontal surface, situated after the downstream end of said ramp and below said first working plane;
an additional conveyor associated to at least said window and aimed at moving, cooperating with said first moving means, odd layers from said support surface to said first surface while allowing even layers coming from said support surface to pass through the window, thus directing the even layers, due to gravity, onto said stationary descending ramp;
second moving means for moving each even layer to said ramp and conveying said even layer to said second surface; third means for moving each even layer onto said second surface, situated below, with said even layer moving with the same speed as the corresponding odd layer, conveyed thereover by said first moving means on said first working plane.